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Microsoft Corp. is working with the OPC Foundation to enable almost any IIoT scenario using interoperability between the millions of OPC UA-compliant applications and equipment. Microsoft will enable IIoT users to connect manufacturing equipment and software with extended support of OPC UA's open-source software stack. Microsoft’s extended support for OPC UA spans its IoT offerings from local connectivity with Windows devices to cloud connectivity via Microsoft Azure. Integration with Azure IoT allows customers to easily send OPC UA data to the Azure cloud, as well as command and control OPC UA devices remotely from the Azure cloud.
Pepperl+Fuchs broke ground June 2 on its new U.S. distribution and engineering center in Katy, Texas, near…

While routine build-up and clogging in process applications is annoying, process scaling is more persistent, causes unplanned downtime and increases costs in many industries. It's typically composed of calcium carbonate, wax, grease or similar…

Just as you can't have too many friends, level measurement applications can't get enough ease of use, reliability and safety. Thanks to increasing process industry needs and user demand for them, these are the three unifying priorities that drove…

Our panel of experts explore best practices for dealing with buildup on chemical seals of a differential pressure flowmeter.

Q: We have a venturi flowmeter with 3-in. flanged pressure taps and flanged chemical seals with capillary tubes in a 44-in. vertical pipe (Figure 1). The fluid is hydrocarbon (polymeric) gas. The problem is that the chemical seal diaphragms often…

A Control Design reader writes: We have several temperature, pressure and flow sensors on a new medical-device cleaning skid that we are developing. These instruments are connected to a PLC as 4-20 mA inputs, and there is also a 4-20 mA output used to control a pump motor speed. A recent failure of a flow sensor brought the process skid instrumentation to my company's quality manager's attention. He asked how we know that the temperatures, pressure and flow are accurate, and how do we know that we are cleaning properly.
I've been tasked to write a procedure for troubleshooting, calibrating and testing the 4-20 mA instruments on the skid. I can probably stumble through this, but what are some best practices for troubleshooting the analog…

Control's Monthly Resource Guide brings you the latest online resources on a variety of process control topics.

MULTI-PART WEIGHING
This four-section webpage by Omega Engineering covers "Weighing Applications," "Weighing System Design," "Installation and Calibration" and "Specialized Installations." The whole group is located at…

FOPDT model has demonstrated utility for controller tuning rules, for structuring decouplers and feedforward control algorithms.

A first-order plus deadtime (FOPDT) model is a simple approximation of the dynamic response (the transient or time-response) of a process variable to an influence. It’s also called first-order lag plus deadtime (FOLPDT), or “deadtime” may be…

'To the degree networks and standards can provide easy, consistent and seamless access to device-resident controls, the vision of truly distributed control may finally dawn upon us.'

Every compressor in the facility went down at once that day, when a PLC redundancy switchover didn’t transfer in time. The engineers didn’t know that each P453 remote I/O processor had a dip-switch-selectable timeout setting—if it didn’t…

A Control Design reader writes: We have several temperature, pressure and flow sensors on a new medical-device cleaning skid that we are developing. These instruments are connected to a PLC as 4-20 mA inputs, and there is also a 4-20 mA output used to control a pump motor speed. A recent failure of a flow sensor brought the process skid instrumentation to my company's quality manager's attention. He asked how we know that the temperatures, pressure and flow are accurate, and how do we know that we are cleaning properly.
I've been tasked to write a procedure for troubleshooting, calibrating and testing the 4-20 mA instruments on the skid. I can probably stumble through this, but what are some best practices for troubleshooting the analog…

Most public utilities deliver basic power and water, and God bless them for doing it. However, a few go beyond their essential missions, and seek to further enhance the overall well-being and prosperity of their communities.
One of these is…

Advanced control on fuel and steam can control emissions while saving millions.

It’s no secret that advanced process control (APC) has played a major role in the process industries for many decades. However, while many organizations focus only on major process units, there’s often an untapped opportunity to do more, and…

Our readers tell us who they think delivers the best technology in our industry

There's knowledge in our readers. That's why every year we ask our loyal audience to help us determine which automation service providers offer the best products and brands they can rely on to get the best combination of performance, ease of use,…

Just when it seems like today’s sophisticated motors and drives can’t possibly add more efficiencies and capabilities, engineers conjure up new tricks and refinements, followed by end users and system integrators who materialize new settings and…

Control's monthly guide brings you invaluable industry information to stay up to date on the latest trends and developments.

THE CLASSIC VALVE BOOK
The fourth edition of the 295-page classic text, "Control Valve Handbook," by Fisher Controls International and Emerson Process Management reports this classic text has been a primary reference since its first printing in1965.

Control's monthly guide brings you invaluable industry information to stay up to date on the latest trends and developments.

THE CLASSIC VALVE BOOK
The fourth edition of the 295-page classic text, "Control Valve Handbook," by Fisher Controls International and Emerson Process Management reports this classic text has been a primary reference since its first printing in1965.

Just when it seems like today’s sophisticated motors and drives can’t possibly add more efficiencies and capabilities, engineers conjure up new tricks and refinements, followed by end users and system integrators who materialize new settings and…

Actionable information is essential for the effectiveness of the 'loop,' as it is for closed-loop control and open-loop alarms.

When I sat down in my office this morning, I was greeted by the operations manager, who pointed out an entry from last night’s operations log: “Did you see? The boiler steam vent is in manual because the pressure reading whacked out and made the…

Actionable information is essential for the effectiveness of the 'loop,' as it is for closed-loop control and open-loop alarms.

When I sat down in my office this morning, I was greeted by the operations manager, who pointed out an entry from last night’s operations log: “Did you see? The boiler steam vent is in manual because the pressure reading whacked out and made the…

Actionable information is essential for the effectiveness of the 'loop,' as it is for closed-loop control and open-loop alarms.

When I sat down in my office this morning, I was greeted by the operations manager, who pointed out an entry from last night’s operations log: “Did you see? The boiler steam vent is in manual because the pressure reading whacked out and made the…

Our readers tell us who they think delivers the best technology in our industry

There's knowledge in our readers. That's why every year we ask our loyal audience to help us determine which automation service providers offer the best products and brands they can rely on to get the best combination of performance, ease of use,…

Visualizing and contextualizing safety data can have a positive impact on productivity and compliance.

"Information is one thing, but safety information is quite another," says George Schuster. He should know. He’s charged with business development for the Global Safety Team of Rockwell Automation and has seen many plants and factories begin to…

How to deal with the constraints of putting access points in hazardous areas.

In an ideal world, it wouldn’t be necessary to worry about explosive atmospheres. Unfortunately, plant environments are far from ideal, with most process plants being about 80% Class I, Div. 2 (Zone 2) and another 10% Class I Div. 1 (Zone 1), so…

Key is to learn as much as possible to make digital technologies safe, secure and successful in process settings.

As usual, and I’m sure this is true for many of you, this year’s autumn season has been a frantic dash of work, deadlines, sleep deprivation, indigestion and suspiciously arthritic stiffness. In my case, this means covering all sides of the…

With today’s network technology, even Ethernet and wireless are almost always fast enough.

As automation professionals, one issue we have about control loops is ensuring we're able to support real-time control. Historically, when Ethernet was 10 MB/s and there were multiple drops on a single port, collisions were a significant concern and…

With today’s network technology, even Ethernet and wireless are almost always fast enough.

As automation professionals, one issue we have about control loops is ensuring we're able to support real-time control. Historically, when Ethernet was 10 MB/s and there were multiple drops on a single port, collisions were a significant concern and…

Because they're the crossroads, nexus and Grand Central Station for sensor signals and data arriving and requests and actuation instructions departing, it's a big help that I/O and terminal blocks are more flexible and capable than ever.

Compact, Remote I/O for Zone 2/Div 2
LB System remote I/O has more power in less space with high-performance, compact modules plugged into a backplane. Energy-saving power management and low-power dissipation allow maximum packing density. With the…

Be just 33 seconds more productive each hour, and the savings mount quickly.

Rockwell Automation previewed its new, forward-looking App Platform for mobility at this week’s TechED conference in Orlando. While focused first on redefining smartphone use on the plant floor – with the aim of making individual workers more…

Control’s latest State of Technology report delves into the many aspects of power systems of interest in process plants.

From sourcing and ensuring uninterrupted flows of clean electricity to monitoring, regulating and metering generation and consumption throughout a facility, process automation professionals who want a smooth-running, efficient and reliable facility are well advised to seek and control power.
This anthology of recent articles delves into the many aspects of power systems of interest in process plants. Remote and wireless systems are speeding development and standardization of energy harvesting and improved battery systems.
Line-powered supplies that used to only transform electricity and maybe offer surge protection are now monitoring and measuring current and voltage profiles, implementing alerts and alarms, and sending data up to…

Greg: Here we take advantage of the chance to talk to Bill Thomas, who provides a great lesson of how to succeed in advancing capabilities and opportunities in his career and the control systems for which he was responsible. His career and the…

Control's monthly guide brings you invaluable industry information to stay up to date on the latest trends and developments.

AT THEIR BEST, ALL THE TIME
ExperTune’s white paper, “How to Improve Performance of Process Control Assets,” by George Buckbee, P.E., describes the practice of real-time asset performance management, shows how to get assets to perform at their best all the time, and demonstrates the value of integrating these tools for a performance picture that delivers financial results. It’s available here.
ISA / www.isa.org
ANALYZING, PREDICTING PROBLEMS
This 57-minute video, “Avoid Equipment Surprises: Predictive Diagnostics for Oil & Gas,” is presented by Joe Dupree, GE Automation and Controls, and users from NiSource Gas and Alyeska. They demonstrate condition-based monitoring, predictive analytics and other tools for evaluating…

Steve Christian remembers the days—not too long ago—when production schedules were printed on sheets of paper and distributed to operators at his plant, who would manually twist valve handles to send the Ragu sauce tomato slurry from one kettle…

Advanced control on fuel and steam can control emissions while saving millions.

It’s no secret that advanced process control (APC) has played a major role in the process industries for many decades. However, while many organizations focus only on major process units, there’s often an untapped opportunity to do more, and…

Find and slay the dragons lurking in the typical safety instrumented system.

Cybersecurity is a growing concern in the process industries, and a number of good articles have been written about it for industrial control systems (ICS)—many full of doom and gloom. Here, we will divide the ICS into two parts: safety…

Big data can only help users if they understand what it is, how it can affect their controls and processes, and how they can use it to optimize operations.

Similar to any new technology emerging on the process control front, big data can only help users make better decisions if they understand what it is, how it can affect their controls and processes, and how they can use it to optimize operations.

Our readers tell us who they think delivers the best technology in our industry

There's knowledge in our readers. That's why every year we ask our loyal audience to help us determine which automation service providers offer the best products and brands they can rely on to get the best combination of performance, ease of use,…

Simulation, the game we all can play!

Washington University's (St. Louis, MO) Robert Heider provides a game plan for using simulation in process control.

There are two classes of simulators, ones that require the user to program in FORTRAN, C++, Visual Basic etc. and ones that advertise that these skills are not required. Most of these programs never work the way they should with your process, but usually work well with the sample problems, which are usually very simple or elementary.

Why simulate at all? From a control systems engineer's viewpoint, it is helpful to be able to predict the dynamics thereby gaining the knowledge of how loops may behave as well as allowing the simulation to be used as a training tool. The chemical engineers want to have some data to support the plant design and a simulator will help justify equipment design and sizes.

I have been asked to sit in on many discussions and vendor presentations about simulators. The subject comes up about what type of physical property database to use or how their product interfaces to the users database or how to enter physical and chemical properties of compounds not in their database. Clearly, this is the single most important factor from the chemical engineering simulation viewpoint. They usually divert their discussion to the DIPPR database while my mind keeps wondering about the dynamics that they say they have, usually as an option. Most of these products require a large cash outlet as well as ongoing customer support from some hot line or email service.

Control DeficienciesWhen you use one of these simulators for control, there are some watchouts; does you simulator actually simulate the following:

Can the dynamics simulate true deadtime? This is important because if it weren't for deadtime, most process control engineers would be out of a job. The control blocks should emulate real time as much as possible and therefore need deadtime. If your simulator does not do deadtimes, do not give up, it must do first order filtering. Just add multiple first orders in series, which looks like a first order with deadtime. This may not be sufficient, as I will explain later.

Noise simulation: This is necessary where analytical control is being implemented, noise needs to be filtered which adds lag to the process. The simulator should be able to add Gaussian noise with an adjustable standard deviation. This is very important for analytical data. Remember if the process model is only 85% accurate, it is good enough for process control. Frequently other engineers are very possessive and not willing to let others see the model because if is not accurate enough. For control purposes, accuracy is not required, just some overall dynamic behavior. The difference of 10% one way or another usually doesn't effect control simulations. Remember the objective of the simulator is to show the approximate behavior, and test various control strategies.

Simulated Physical PropertiesThis is the major watch out one should have with commercial packages. In order for the simulator to produce good results, you need a good estimate of the physical properties. How do they get these properties in their database? They perform regressions on experimental data or they use some equations based on molecular structure. If the data is experimental, what data did they use? Over what range was the data regressed? Frequently the data entered is only based on a few points and well outside the range where you may want to run your simulation. A good example of this is formaldehyde and water solutions.

An Actual ExampleIn order to minimize the size of a surge tank, a commercial package, with dynamic properties, was used to simulate a process chilled cooling system using a 50-50 mixture of ethylene glycol and water as the cooling medium. Forty percent of the system capacity is a batch process so there was some concern that a large surge tank is in place in order to allow the chiller to maintain the utility at the desired temperature.

A commercial simulator was used to test the effect of various size surge tanks on dynamic response of the chiller's outlet temperature controller.

The first problem was the apparent inability of the simulator to calculate the viscosity of the glycol and water mixture. The simulator gave a viscosity several times the viscosity given by the vendor of the ethylene glycol and water solution. The density given was also in error. I question how these packages simulate liquid mixtures.

Once the simulation was configured, it showed that there was no control problem and that the return temperature changed instantaneously and as a result no surge capacity was required! This, of course, cannot be. The simulation failed to show the effect of the installed deadtime due to the piping. This turned out to be a very important criterion, because the liquid in the piping acted as surge capacity.

Piping should be considered both as a delay line and as surge. Consider the following:

The pipeline, 1000 feet in length (500-foot supply and return branches) of 6" SCH40 pipecontains 1.5 gal/foot. When flowing at 600 GPM or 6.6 feet/second, the total delay per branch would be 500/6.6 or about 75 seconds. With a sample time of 5 seconds this would be 75/5 = 15 pipe segments with 500/15 = 33 feet/segment which is 33.33 feet/segment * 1.5 gal/foot = 50 gal/ segment.

In this case, it became necessary to simulate the pipeline as a series of 50 gallon tanks, the idea that deadtime can be simulated as a series of first order lags. Once this change was made, to the simulation, the simulator showed the first order effect, but still failed to show the effect of true deadtime. The system was finally simulated in EXCELÃ¢ to control the integration scan time, which was necessary to see the effect of the piping deadtime. Once the simulation was complete, it demonstrated that there is sufficient reserve of coolant in the supply and return piping to eliminate the surge tank. The following plots show the correct results of the simulation. Notice the dead time between the load temperatures.

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